The present invention was developed to provide an adjustable grading system for the grading of marine animals, and in particular fish, by size. It is known when grading fish, to use a grading system which comprises a grate formed from a plurality of parallel fixed, spaced apart bars or rods. As the bars or rods are fixed, it is not possible to change their spacing in order to vary the size of the fish which can pass through the grate. In order to grade fish of different sizes, a plurality of grates are required where the bar or rod spacing is different.
The present invention was initially developed with the view to providing an adjustable grading system for marine animals. However it has been discovered that embodiments of the invention have a much broader application and can be used for grading many types of articles by size and moreover can be used to evenly space articles.